This invention relates to a target assembly adapted for use with a particle accelerator to generate neutrons. In more detail, the invention relates to an accelerator-breeder plant consisting of a novel target assembly composed of a neutron emissive target material which target assembly is driven by a linear accelerator producing a high intensity beam of protons and drives a blanket containing fertile material.
An alternative to the production of fissile material in an enrichment plant or a fast breeder reactor is to employ an accelerator-breeder plant. In an accelerator breeder plant neutrons produced by directing a high power, high current proton beam into a suitable target material are absorbed in a suitable breeding blanket. No feasible design has yet been suggested for the target/blanket portion thereof.
Target design involves a balance between (1) physics of neutron and heat production in the target, (2) thermal-hydraulics of heat removal from the target, (3) materials performance in the proton/neutron field of the target, (4) efficient transfer of neutrons from target to blanket, and (5) blanket design constraints on peak power density, radial and axial power distribution, and fissile production distribution. Power densities typical of solid, high mass number, targets are impossible to cool for beam powers of the order of 300 MW (1 GeV, 300 mA). Three options are open: (1) operate at a beam power much lower than 300 MW, (2) operate with a flowing molten target using the heat capacity of the target material to carry away the heat, or (3) devise a way to distribute the thermal power production in the target over a much greater distance in the axial (i.e. beam) direction so as to reduce the power density. Use of a reduced beam power implies an undesirable lower fissile production rate. Mechanical design problems for flowing molten targets at the 300 MW beam power level are formidable, and a practical design is probably infeasible. Further, the low height-to-diameter ratio of the neutron production volume in high mass number molten targets results in a significant fraction of the neutrons born in the target not reaching the radial blanket. Thus this invention relates to the third design option.